JP4654575B2 - Cylindrical battery and inter-battery connection structure using the same - Google Patents

Description

  In the battery having the spiral electrode group, the present invention improves the current collector bonded to the lower part of the electrode group, strengthens the bonding with the case as the negative electrode terminal by forming a groove, and further uses the connection body to The present invention relates to a structure for mechanically fitting and connecting between batteries.

  There are various types of cylindrical alkaline storage batteries. Typical examples are nickel-cadmium storage batteries and nickel-hydrogen storage batteries. These are highly reliable and easy to maintain. Widely used in applications. In recent years, there has been a demand for the development of a cylindrical storage battery suitable for large current discharge as a power source for a battery with electric assistance, a lawn mower, and an electric vehicle.

  In such a large-current cylindrical battery, a pair of long positive and negative plates in a strip shape are spirally wound through a separator for separation and housed in a metal battery case.

  In addition, as the input / output current collecting structure from the electrode plate suitable for a large current, a plurality of rectangular current collectors are provided on each end of the electrode plate protruding outward from the upper and lower end surfaces of the electrode group. The battery case and the negative electrode current collector are welded at a single point to the bottom center of the case by a welding electrode rod of about φ3 mm inserted into the through hole in the center of the current collector and the welding electrode placed at the bottom of the case. (For example, Patent Document 1).

Further, in the inter-battery connection structure in which the connection body arranged between the batteries is connected to the sealing body of one battery and the case of the other battery in order to connect the cylindrical batteries in series, generally the flat portion of the connection body Is welded to the sealing plate of one battery, and the cylindrical part of the connection body is resistance welded to the bottom of the side surface of the other battery case (for example, Patent Document 2).
Japanese Patent Laid-Open No. 11-031497 JP-A-10-106533

  However, since the battery case and the negative electrode current collector are connected at only one point, the connection resistance between the case and the current collector is high. For example, when discharging with a large current of 100 A or more, the case and the negative electrode current collector Since the resistance of the welded part of the body is high, the discharge voltage of the battery is greatly reduced. In addition, the electrode group may move within the case even with a drop impact, and the welded part may come off.

  Further, in the case of connecting the cylindrical batteries in series, it is difficult to position the shallow cylindrical portion of the connection body on the other battery case, and the welding strength varies.

  In view of such problems, an object of the present invention is to provide a battery having high charge / discharge characteristics and excellent impact resistance with high reliability. Furthermore, the structure which can connect these batteries simply in series is provided.

The positive electrode plate of the cylindrical battery according to the present invention protrudes the core material at the upper end portion in the width direction upward, and the negative electrode plate protrudes the core material at the lower end portion downward and is wound in a spiral shape, and The positive electrode current collector welded to the core material protrusion of the positive electrode plate protruding upward of the electrode group, the negative electrode current collector welded to the core material protrusion protruding downward, and containing these inside and containing the negative electrode It consists of a metal case that also serves as an input / output terminal, and a sealing body that seals the case and is electrically insulated from the case and provided with a cap that also serves as a positive input / output terminal.

  The negative electrode current collector has a bottom surface portion connected to a core material protruding portion that protrudes downward from the negative electrode plate, and a cylindrical shape that rises substantially vertically from the periphery of the bottom surface portion and contacts the inner surface at the bottom of the battery case The cylindrical portion is fixed by forming a concave groove from the outer surface of the battery case at the contact position.

  The cylindrical battery can easily connect the batteries in series by using a connection body that fits into the groove. Further, if the negative electrode current collector and the battery case are welded in the concave groove, the internal resistance is further improved. If welding is performed at the fitting portion with the concave groove portion of the connection body, the positioning can be easily fixed.

  According to the structure of the cylindrical battery of the present invention, the bottomed cylindrical negative electrode current collector and the battery case are mechanically joined by a concave groove from the outer surface of the battery case in addition to normal welding. Therefore, the internal resistance of the battery can be reduced, the battery can be charged / discharged at a high rate, and at the same time, the electrode group is fixed, and the impact resistance is improved. Moreover, it is possible to easily connect these batteries in series by using the concave groove and the battery connector fitted in the groove.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view of a cylindrical battery of the present invention. The electrode group 5 includes a positive electrode plate 1, a negative electrode plate 2, and a separator 6. The positive electrode plate 1 protrudes the core material 3 at the tip portion upward, and the negative electrode plate 2 causes the core material 4 at the tip portion to protrude downward. And spirally wound. The positive electrode current collector 7 welded to the core material protruding portion of the positive electrode plate protruding upward of the electrode group 5, the negative electrode current collector 8 welded to the core material protruding portion protruding downward, and these are housed inside. A metal case 9 also serving as an input / output terminal of the negative electrode, and the case 9 is sealed and electrically insulated from the case 9 and connected to the positive electrode current collector 7 by a connection lead 10 at the upper side. The negative electrode current collector 8 has a bottomed cylindrical shape connected to the projecting core member projecting downward, and the case 9. A cylindrical battery in which the contact portion of the cylindrical portion of the case 9 and the negative electrode current collector 8 is mechanically joined by forming a concave groove 12 in the case 9. is there.

  FIG. 2 is a schematic cross-sectional view of a process of forming the concave groove 12 in the case 9 in order to mechanically join the abutting portion of the cylindrical portion of the case 5 and the negative electrode current collector 8. The groove is formed by rotating the machine 13 and the battery together. At this time, the depth of the groove is preferably 0.2 to 1.0 mm. The groove protrudes into the case, but the electrode group 5 is protected by the cylindrical portion of the negative electrode current collector to prevent damage.

  Further, the negative electrode current collector 8 and the groove portion 12 of the case can be welded, and FIG. 3 shows an example of a process of welding the negative electrode current collector 8 and the groove portion 12 of the case 9. The welding electrode 14a is inserted into the central portion of the electrode group 5, pressed against the bottom surface of the negative electrode current collector 8, the welding electrode 14b is disposed outside the concave groove portion 12, and a current flows between the welding electrodes 14a and 14b. Thus, the negative electrode current collector 8 and the case 9 can be welded.

FIG. 4 is a schematic cross-sectional view showing the configuration of the inter-battery connection of the present invention. The batteries X and Y connected by the connection body 15 are of the same type and standard of the present invention, and the sealing body 11 of the battery X, The batteries X and Y are connected in series by connecting the battery Y to the case 9 with the connecting body 15. The projection 15 a of the cylindrical portion of the connection body 15 is fitted into a case groove 12 provided on the back side where the cylindrical portion 8 a of the negative electrode current collector 8 of the battery Y contacts the case 9.

  Further, the projection of the connection body 15 and the battery groove portion 12 can be welded. For example, FIG. 5 is a schematic cross-sectional view showing the configuration of the inter-battery connection of the present invention, and it is possible to weld a pair of welding electrodes 14c against the projection 15a and the case 9 of the connection body and energize them. .

  Next, specific examples of the present invention will be shown. The battery A having the bottomed cylindrical negative electrode current collector 8 has a diameter of 33 mm, a height of 61 mm, and a nominal capacity of 6000 mAh, and this configuration method will be described in detail below.

  Using a sintered nickel positive electrode having a thickness of 0.5 mm and a hydrogen storage alloy negative electrode having a thickness of 0.3 mm, each electrode plate is provided with a core portion protruding at the tip in the width direction. The separator 6 was interposed in between so that the material portions protruded up and down about 1.5 mm above and below the electrode group, respectively, and the whole was wound spirally to form an electrode group 5 having a diameter of 30 mm and a height of 50 mm.

  A rectangular current collector 7 having a diagonal length of 27 mm is disposed directly above the upper end surface of the electrode group 5, and the exposed core member 4 on the lower end surface of the electrode group 5. Were welded to the exposed core member 4 at a plurality of locations using a pair of welding electrodes while contacting the bottomed cylindrical negative electrode current collector 8. The electrode group 5 is inserted into a metal case 9, and a disk-like grooving machine 13 is applied to the contact portion between the case 9 and the cylindrical part of the negative electrode current collector 8, and the grooving machine 13 and the case 9 are rotated. Then, a concave groove 12 having a depth of 0.4 mm was formed in the case 9. Further, the central portion of the negative electrode current collector 8 is pressurized through one welding electrode rod 14 a to the central through hole portion of the positive electrode current collector 7, and the other welding electrode 14 c is pressed against the concave groove 12 of the case 9. The current collector 8 and the case 9 were welded. Next, a predetermined amount of alkaline electrolyte is injected into the metal case 9 from the central through hole of the positive electrode current collector 7, and then the end of the connection lead 10 provided on the positive electrode current collector 7 serves as a positive electrode terminal. 11, and the opening of the case 9 was sealed with the sealing body 11 to produce the battery A of the present invention.

  For comparison with the battery A, a battery was produced in which the depth of the concave groove 12 formed in the contact portion between the case 9 and the negative electrode collector cylindrical portion was changed. The depth of the concave groove of the battery B was 1.0 mm, the battery C was 0.6 mm, the battery D was 0.2 mm, and the battery E had no concave groove. FIG. 8 is a schematic cross-sectional view of the battery E.

  Using these five batteries, the internal resistance was measured and compared. The battery was discharged at room temperature (25 ° C.) at a current value of 2 A until the battery voltage became 0.9 V, and then charged at a current value of 6 A for 30 minutes. Next, after resting for 1 hour, the battery was discharged at a current value of 25 A for 20 seconds, and the battery voltage at 10 seconds was measured. Next, after charging the discharged capacity, similarly, discharging was performed at a current value of 50A, 75A, and 100A for 20 seconds, and the battery voltage after 10 seconds was measured. The battery voltage after 10 seconds thus obtained was taken as the vertical axis, the current value was taken as the horizontal axis, and the slope of the straight line in the IV characteristic was determined, and the value was taken as the internal resistance of each battery.

  The relationship between the depth of the groove 12 and the internal resistance of the battery was as shown in FIG. It can be seen that the internal resistance of the battery A having the groove depth of 0.4 mm is the lowest. This is because the deeper the concave groove, the larger the junction area between the negative electrode current collector and the case, and the shorter the path through which current flows from the negative electrode current collector to the case (negative electrode terminal). I think that is possible. However, when the groove depth is larger than 0.4 mm, the internal resistance increases. When these batteries were disassembled and the inside of the batteries was examined, the cylindrical portion of the negative electrode current collector 8 was bent inside, and the battery group 5 was damaged. This is considered to be because the increase in the resistance of the battery group due to the electrode plate breakage exceeded the effect of the resistance reduction due to the expansion of the joint area between the negative electrode current collector 8 and the case 9. In addition, the incidence rate of an internal short circuit can be restrained low by making groove depth into 1.2 mm or less.

  Moreover, since the electrode group 5 is completely fixed by the upper and lower grooves of the battery case 9, the drop resistance of the battery alone is also improved. FIG. 7 shows the result of the drop test. The batteries A to E were dropped from a height of 2 m at a number of N of 10 consecutively 20 times in the positive electrode terminal downward direction, the negative electrode terminal downward, and the battery lateral direction.

  The battery E without the concave groove 12 is short-circuited by three, whereas the battery with the concave groove 12 is one or less, and the effect is high particularly when the groove depth is 0.4 mm or more.

  Furthermore, it is possible to easily connect these batteries in series using the concave groove 12 formed in the contact portion of the cylindrical portion of the case 9 and the negative electrode current collector 8. The bottom surface portion of the connection body 15 is welded to the sealing plate 11 of one battery X, and the cylindrical portion of the connection body 15 has four projections 15a projecting inward, and this projection 15a is connected to the other battery. These batteries can be mechanically connected by fitting into the groove 12 on the negative electrode side of Y. Further, when welding is performed from above the projection 15a of the connection body 15, the resistance between the batteries further decreases, and the output of the assembled battery becomes higher.

  As described above, according to the present invention, it is possible to charge and discharge at a high rate and to provide a battery having excellent impact resistance with high reliability. Moreover, between batteries can be simply connected in series using a concave groove provided on the outer surface of the battery and a connection body fitted to the groove.

  Such a configuration is not limited to a cylindrical alkaline storage battery, but can be applied to other battery systems in which a spiral electrode group is housed in a battery case. Further, the present invention is not limited to a cylindrical shape, and may be applicable to a case where an electrode group wound in a rectangular tube shape is housed in a rectangular tube battery case.

1 is a schematic longitudinal sectional view of a cylindrical battery according to an embodiment of the present invention. The longitudinal cross-sectional schematic diagram which shows the grooving process to the cylindrical part of the case and negative electrode collector which concern on one Embodiment of this invention The longitudinal cross-sectional schematic diagram which shows the welding process of the groove | channel to the cylindrical part of the case and negative electrode collector which concerns on one Embodiment of this invention The longitudinal cross-sectional schematic diagram which shows the structure of the connection structure between batteries which concerns on one Embodiment of this invention. The longitudinal cross-sectional schematic diagram which shows the welding process in the battery connection which concerns on one Embodiment of this invention. Diagram showing the relationship between groove depth and internal resistance Diagram showing the relationship between groove depth and number of short circuits in drop test Longitudinal cross-sectional schematic diagram of a conventional cylindrical battery

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode plate 2 Negative electrode plate 3 Core material of positive electrode plate front-end | tip part 4 Core material of negative electrode plate front-end | tip part 5 Electrode group 6 Separator 7 Positive electrode collector 8 Negative electrode collector 9 Battery case 10 Connection lead 11 Sealing body 12 Concave Groove 13 Grooving machine 14 Welding electrode 15 Connector

Claims (5)

An electrode group in which one end in the width direction protrudes upward and a negative electrode plate in which the other end in the width direction protrudes downward are spirally wound through a separator, and the electrode group protrudes above the electrode group A positive electrode current collector welded to the end of the positive electrode plate, a negative electrode current collector welded to the end of the negative electrode plate projecting downward, and a metal case that accommodates these and also serves as an input / output terminal for the negative electrode And a sealing body that is electrically insulated from the case and sealed with a cap that also serves as an input / output terminal of the positive electrode, and the negative electrode current collector has a bottomed cylindrical shape. A position of the bottom surface portion connected to the downward projecting core member and a cylindrical portion that rises substantially perpendicularly from the periphery of the bottom surface portion, and the cylindrical portion abuts on the inner surface of the battery case cylindrical collector for fixing the tubular part from the outside to form a groove in . 2. The cylindrical battery according to claim 1, wherein the concave groove has a depth of 0.2 to 1.0 mm. 2. The cylindrical battery according to claim 1, wherein the cylindrical portion of the negative electrode current collector and the case are resistance-welded or laser-welded in the groove portion. The inter-battery connection structure in which the connection body disposed between the batteries is joined to the sealing body of one battery and the bottom portion of the other battery case in order to connect the cylindrical batteries according to claim 1 in series. A battery-to-battery connection comprising a flat part welded to the sealing body of the battery, and a cylindrical part having a protrusion fitted into a groove formed to join the negative electrode current collector of the other battery and the case Construction. 5. The inter-battery connection structure according to claim 4, wherein the protrusion of the connection body and the battery concave groove are resistance welded or laser welded.

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